1. Field of the Invention
The present invention relates to a magnetic recording apparatus having an improved structure of a motor and a motor frame, and more specifically, relates to a thin magnetic recording apparatus in which the heights of the motor and the frame are reduced.
2. Background of the Invention
FIG. 7 is an exploded perspective view of a conventional magnetic recording apparatus disclosed in Japanese Patent Laid-Open No. 6-220586. FIG. 8 illustrates a motor accommodation state as viewed from point A in FIG. 7. These figures depict a magnetic recording apparatus, generally indicated by reference numeral 66, including a carriage mechanism 55, a medium driving motor 63, a control circuit board 64, and a frame 65.
A carriage mechanism 55 includes components 50 to 54. Reference numerals 50 and 51 denote magnetic heads. An arm 52 supports the magnetic head 50. A carriage 53 that supports the magnetic head 51 also supports the arm 52 swingably at one end. A stepping motor 54 step-moves the carriage 53 in the radial direction of a recording medium (not shown).
The medium driving motor 63 includes components 56 to 62. A stator 56 has coils 56a each of which is formed by winding a wire on a tooth-like pole in three layers. A rotor 57 is disposed such that a rotor magnet 57a is opposed to the tooth-like poles of the stator 56. A hub portion 58 that is provided in the rotor 57 holds the recording medium. Reference numeral 59 denotes a rotary shaft provided in the rotor 57, and numeral 60 denotes a bearing of the rotary shaft 59. A bearing fixing portion 61 is formed on a frame (described later). Reference numeral 62 denotes a stator cover.
Reference numeral 64 denotes a control circuit board for controlling operations of the carriage mechanism 55 and the medium driving motor 63.
Reference numeral 65 denotes a frame in which the carriage mechanism 55 and the medium driving motor 63 are fixed or accommodated. Reference symbol 65a denotes a bottom plate and symbol 65b denotes a coil accommodating portion 65b. Predetermined portions of the coil accommodating portion 65b are pressed by press working to reduce the thickness of the frame 65 there. Reference symbol 65c denotes strain escape holes for escape of the pressed portions.
Referring to FIG. 8, character B represents an interval between the bottom surface of the frame 65 and the top surface of the stator cover 62, i.e., the thickness of the magnetic recording apparatus 66. Character C represents the thickness of the frame 65 and character D represents a level difference formed through pressing by press working.
In the conventional magnetic recording apparatus 66 having the above-described structure, the coils 56a are partially accommodated in the coil accommodating portion 65b to reduce the height of the magnetic recording apparatus 66, i.e., to make it thinner. However, the reduction in dimension resulting from press working has a certain limit, and hence it is almost impossible to further reduce the thickness of the apparatus 66 by partially thinning the frame 65.
Similarly, even with such forming techniques as aluminum die casting, rather than press working, it is almost impossible to further reduce the thickness of the apparatus 66.
On the other hand, forming holes in the frame 65 at the positions confronting the coils 56a and accommodating the coils 56a there may absorb part of the height of the coils 56a. However, this structure has a problem in that the rigidity of the apparatus becomes insufficient because a large number of holes having large dimensions need to be formed in the frame 65.